EGT Sensor again.

[Sean_S3]

It would appear that my long run of trouble free motoring in over. I had a full service carried out on the car last week and out of curiosity I did some code reading at the weekend to find that the EGT sensor fault is showing again.


17868 Exhaust gas temp sensor 1 (G235) Implausible signal . P1455 - 35 - 10 Intermittent.



I had this sensor replacing less that 2 years ago , can these things fail so quickly ?? Or could it be possible that something else is causing it to fail ?? This fault is the only one registered on the ecu so it doesnt look like its a knock on effect of another problem somewhere else.

Any thought would be appreciated.

Cheers.
Sean.

 

[<tuffty/>]

Wiring fault? I would be tempted to rewire back to the ECU tbh... I had an intermittent knock sensor issue that disappeared when I re wired it directly to the ECU... worth a punt else you could be replacing 180 quids worth of sensor for nowt...

<tuffty/>

 

[aragorn]

Given its "implausible signal" rather than a circuit fault, it could be caused by a failing MAF or dodgy lambda sensor.

The engine ECU calculates a "virtual" EGT as well as taking a measurement from the probe, and if they differ too much the ECU will flag the above code.

IE engine runs lean due to faulty sensor, lean-ness causes high EGT, ECU doesnt expect high EGT because load isnt high enough, pops fault code.

 

[Sean_S3]

Thanks for the replies.

@ Tuffty I dont know if I would be comfortable wiring it up to the ECU but I will take a look at the connection to make sure its actually in right, It may be that it has been knocked while it was in for servicing last week.

@ Aragorn I did consider the MAF but that is a relatively new unit as well , probably around 2 1/2 years old. i think the lambda is the original. Would unplugging the MAF help in checking out this theory ?

For the moment in time I have cleared the fault and when driven steady it doesnt come back , although 2 of the readiness tests still show as failed.

Many thanks.
Sean.

 

[aragorn]

which readiness tests have failed?

Unplugging the MAF will just put the car into limp mode, so wont tell you much at all.

Maybe check the fuel trims in block 32, if they're far out it could help narrow it down to the lambda?

 

[Sean_S3]

The test for emissions and the catalytic converter had failed but they have passed since they were orinially reset at the weekend.
Steady driving is doing the trick as the fault has not come back but I know once on full boost it will reappear.

I dont have the full version on vagcom unfortunatly so any further logging would have to be carried out by my local independant in order to get to the bottom of the problem.

Many thanks.
Sean.

 

[Sean_S3]

Right I now have a registered version of VCDS lite so I am able to tap in to more measuring blocks. What blocks would be worth checking and under what conditions ?? While idling block 118 for the egt was pretty healthy around the 330 c mark which seems reasonable.

Im not convinced the sensor is bad, looking on other forums such as the TT forum and seat cupra forum there are several posts mentioning other problems causing the fault such as poor earth, MAF , strangled TIP etc. Hopefully we can narrow it down to a few possible factors before I spend £200 again getting the sensor replaced.

Cheers.
Sean.

 

[Sean_S3]

I have done some logs tonight logging blocks 001, 031 and 015 , and then another log on blocks 002 , 112 and 115 .
Please take a look and see what you think .

Here is blocks 001 and 031

	Group A:	'001				Group B:	'031
		RPM	Temperature	Lambda	Bin. Bits		Lambda Factor	Lambda Factor
	TIME					TIME
Marker	STAMP	/min	°C	%		STAMP
	764.8	2160	69	-2.3	1101000	765.32	0.992	0.992
	766.12	2240	69	0.8	1101000	766.61	1.008	0.992
	767.43	2120	69	2.3	1110100	767.91	1.367	0.984
	768.72	3480	69	0	1100000	769.14	1.016	0.992
	770.03	3800	69	-8.6	1101000	770.43	0.984	0.961
	771.25	4240	69	-1.6	1101000	771.75	0.945	0.953
	772.66	4680	69	-2.3	1101000	773.15	0.961	0.953
	773.95	5040	69	0	1101000	774.35	0.961	0.953
	775.26	5200	69	-0.8	1110100	775.66	0.836	0.961
	776.67	3280	69	0	1110000	777.07	1.991	1.047
	777.98	2840	69	0	1110000	778.38	1.991	1.047
	779.39	2400	69	0	1110100	779.79	1.991	1.047
	780.69	2040	70	0	1110100	781.09	1.991	1.047
	781.9	1680	70	0	1110110	782.3	1.991	1.047
	783.31	1080	70	0	1110110	783.71	1.991	0.945
	784.51	1720	70	0	1100110	784.93	0.984	0.945

Here is blocks 002 , 115 and 112

Group A:	'002				Group B:	'115				Group C:	'112
	RPM	Load	Inj. On Time	Mass Flow		RPM	Load	Absolute Pres.	Absolute Pres.		Temperature	Load
TIME					TIME					TIME
STAMP	/min	%	ms	g/s	STAMP	/min	%	mbar	mbar	STAMP	°C	%
927.48	2040	14.3	1.7	5.58	926.56	1280	15	1000	1000	926.98	625	0
928.79	2080	30.1	3.4	13.86	927.99	2080	14.3	1000	1000	928.39	640	0
930.19	2160	54.1	5.1	23.14	929.28	2120	51.1	1000	1010	929.68	665	0
931.49	2320	56.4	5.44	25.53	930.69	2200	55.6	1000	1070	931.09	690	0
932.8	2720	134.6	12.58	76.64	932	2440	93.2	1770	1150	932.4	715	0
934.21	3600	191.7	19.04	132.33	933.22	2920	166.2	2510	1930	933.71	750	0
935.62	4440	191.7	17.68	163.86	934.62	3840	191.7	2520	2390	935.12	825	0
936.93	5120	182.7	17.68	178.22	936.03	4640	191.7	2420	2250	936.43	900	0
938.24	5760	172.2	22.1	188.67	937.44	5400	178.2	2290	2090	937.84	955	22.4
939.55	6280	159.4	21.42	187.14	938.74	6000	170.7	2190	1990	939.13	1110	40
940.85	4920	180.5	25.16	191	940.05	6160	65.4	1000	1790	940.45	1110	40
942.06	5040	125.6	17	95.08	941.25	5040	185.7	2310	2260	941.66	1110	29.8
943.37	4120	163.9	23.46	145.5	942.56	4320	12	1000	1210	942.96	1110	25.1
944.78	3360	59.4	8.16	36.81	943.87	3720	12	1000	1360	944.37	1110	20.4
946.19	3240	12.8	0	6.94	945.18	3360	14.3	1000	1190	945.68	1110	20.4
947.6	3160	12.8	0	7.83	946.67	3200	12.8	1000	1040	947.08	1110	19.6
949	3040	12.8	0	7.78	948.09	3120	12.8	1000	1030	948.49	1110	18.8
950.3	2960	34.6	4.42	20.06	949.5	3000	12.8	1000	1030	949.9	1110	18

EGT 's went through the roof and at 955 c the readings bombed out completly.
MAF reading look pretty weak peaking at 187 g/s @ 6280 rpm. I'm certain i've had just above 200 g/s on occasion.
How does block 031 look ?

Any thought would be greatly appreciated.
Thanks.

 

[Booth1982]

Any Luck with this issue???

 

[Sean_S3]

Yes replaced EGT sensor and removed a dodgy remap. No more problems up until the day the car got wrote off.